First, What the heck even is a double mane?!
A double mane refers to a style of horse mane. Typically, horse’s manes – the hair growing from the crest of the neck – sweep to one side or the other of the horse’s neck. The mane may naturally go to the right or to the left, but mane hair nearly always falls on only one side. Horses that have a “double mane” tend to be horses with a very thick mane that has lots of hair. Due to the thickness, the mane may naturally split down the middle creating a full or semi-full mane on both sides of the horse’s neck.
Double manes (occasionally called split manes) are unusual for most horse breeds. Horses with very fine hair – such as Arabians, Quarter Horses, and Thoroughbreds almost always have single-sided manes, and because those are popular horse breeds, a single-sided mane is considered “normal”. In fact, though, in many horse breeds a double mane is not unusual. Horse breeds with thicker manes- such as Morgan horses, Friesians, Gypsy, Andalusians, and other Spanish horse breeds tend to have much thicker manes with longer, more flowing locks and a greater tendancy to fall on both sides of the neck.
While much of this is due to variance in the natural thickness of a horse’s mane, some is due to the fact that in many breed circles it is considered “proper grooming” to “thin” a mane. Thinning a mane consists of using a small metal comb to pull out mane hair strategically so that the mane lies neatly on one side of the horse’s neck.
Thinning is one option for controlling a double mane if your horse’s mane is splitting down the middle and you (or the organization you show in) finds a split mane to be an undesirable trait.
Sometimes when horses grow a mane that naturally falls double, one side will be thicker than the other side, or one side may even appear to be only a partial mane. You can’t really influence how a double mane falls, but you can shape and groom the existing mane.
Managing Double Horse Manes
Double manes can be a hassle to deal with – all that extra hair can get in the way of a rider’s hands or make a horse’s neck even hotter during a warm workout. One way to handle the issues of tidiness and overheating is to make adding a running braid a part of your regular tacking-up routine. The running braid can be done in a single braid by flipping both sides of the double mane onto one side of the neck before braiding, or you can do a running braid down each side (how I prefer to braid my own horse’s thick double mane). Doing a double running braid requires a lot of volume in the mane, but if the thickness and length are present, it is possible to do a running braid down each side of the neck.
Double manes are somewhat rare and in some cases undesirable, but it all comes down to preference. If you like a double mane you can help your horse grow thicker longer hair using good grooming techniques that promote hair growth and supplements to help hair growth.